Vehicle propulsive aerodynamic elements

ABSTRACT

Drag reducing systems for vehicles are provided. In one aspect, a drag reducing system generally includes an airfoil rotatably couplable to the vehicle and configured to provide a lift force to the vehicle as a result of differential airflow velocity over the upper surface with respect to the lower surface. The drag reducing system may further include a flow alignment vane to rotationally align the airfoil to the direction of airflow. In another aspect, a drag reducing system generally includes an air vane hingedly couplable to a surface of a vehicle and configured to rotate from a first stowed position to second deployed position. The air vane includes a flared leading portion to provide a force to bias the air vane toward the first position and a flared lateral portion to provide a force to rotate the air vane to the second deployed position.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Nos. 62/490,991, filed Apr. 27, 2017, and 62/642,882, filedMar. 14, 2018, the disclosures of which are hereby expresslyincorporated by reference herein in their entirety.

BACKGROUND

Numerous means have been sought to improve the fuel-efficiency of movingbodies and, especially, moving bluff bodies by reducing theiraerodynamic drag. In the field of surface transportation, andparticularly in the long-haul trucking industry, even small improvementsin fuel efficiency can reduce annual operating costs significantly. Itis therefore advantageous in the design of a vehicle to reduce dragforces, thereby increasing the aerodynamic properties and efficiency ofthe vehicle.

The over-the-highway cargo-hauling tractor-trailer combination is onevehicle that experiences excessive aerodynamic drag. Generallydescribed, tractor-trailer combinations typically include a tractorhaving a so-called fifth wheel by which a box-like semi-trailer may beattached to the tractor by an articulated connection for transportationof the cargo trailer.

It is well known that bluff bodies, such as trailers, contributesignificantly to aerodynamic drag, as evidenced by the formation of awake along the length of and in the trailing region behind the trailer.The generation of the wake, formed by eddies, can be contributed to theshape of the conventional trailer, which is essentially a rectangularbox having a flat, rectangular roof along with flat, rectangular sidepanels. The fore and aft vertical surfaces of such trailers are alsogenerally flat rectangular surfaces. As such, current bluff bodies, suchas the conventional trailer, which are generally suitable for use withtractors of Class 8 and other types, suffer from a low pressure zone atthe rear of the trailer such that the air stream suffers from earlyseparation, resulting in a broad eddying wake forming downstream of theseparation. Trailers in motion also experience aerodynamic dragresulting from crosswind yaw conditions. Crosswinds result in verticalairflow up the sides of the trailers. The airflow separates from the topof the trailer, forming a strong cone vortex that increases drag andreduces vehicle efficiency. The net result is the creation ofconsiderable aerodynamic drag.

SUMMARY

In accordance with one embodiment of the present disclosure, a dragreducing assembly is provided. The drag reducing assembly generallyincludes an airfoil rotatably couplable to a mounting surface, theairfoil having a leading edge, a trailing edge, an upper surface, and alower surface, the airfoil configured to provide a lift force to thedrag reducing assembly as a result of differential airflow velocity overthe upper surface with respect to the lower surface; a flow alignmentvane associated with the airfoil configured to provide a rotationalalignment force to position the airfoil in a direction associated withthe airflow; and a partition panel positioned between the airfoil andthe flow alignment vane configured to separate the airflow over theupper and lower surfaces of the airfoil from the airflow interfacingwith surfaces of the flow alignment vane, wherein the upper surface ofthe airfoil may have a longer distance between the leading edge and thetrailing edge than the lower surface of the airfoil to generate the liftforce.

In accordance with another embodiment of the present disclosure, a dragreducing system for a vehicle is provided. The drag reducing systemgenerally includes a surface of the vehicle, a mounting pin couplable tothe surface, the mounting pin defining an axis; an airfoil rotatablycouplable to the mounting pin, the airfoil having a leading edge, atrailing edge, an upper surface, and a lower surface, the airfoilconfigured to provide a lift force to the aerodynamic assembly as aresult of differential airflow velocity over the upper surface withrespect to the lower surface; a flow alignment vane associated with theairfoil configured to provide a rotational alignment force to rotate theairfoil about the axis to a position directionally associated with theairflow; and a partition panel positioned between the airfoil and theflow alignment vane configured to separate the airflow over the upperand lower surfaces of the airfoil from the airflow interfacing withsurfaces of the flow alignment vane.

In accordance with another embodiment of the present disclosure, a dragreducing system for a bluff body having a length and a height isprovided. The drag reducing system generally includes an air vanehingedly couplable to a surface of the bluff body, the air vane having abody portion, a leading portion, a lateral portion, an upper surface,and a lower surface, the air vane configured to rotate from a firstposition, wherein the air vane may be positioned adjacent to thesurface, to a second position, wherein the air vane may be positionedprojecting at an angle away from the surface, wherein the leadingportion may be flared inward toward the surface in the first position toprovide a force to bias the air vane toward the first position when theairflow along the surface is aligned with the length of the bluff body,wherein the lateral portion may be flared away from the surface in thefirst position to provide a force to rotate the air vane from the firstposition toward the second position when the airflow along the surfacehas a directional component upward along the height of the bluff body.

In accordance with any of the embodiments disclosed herein, the dragreducing assembly may further include a mounting assembly for rotatablycoupling the airfoil to the mounting surface, the mounting assemblyhaving a base plate couplable to the mounting surface and a pin definingan axis, wherein the airfoil is configured to rotate about the axis inreaction to the rotational alignment force.

In accordance with any of the embodiments disclosed herein, the pin mayinclude a friction reducing bearing to facilitate rotation of theairfoil in reaction to the rotational alignment force.

In accordance with any of the embodiments disclosed herein, the mountingsurface may be a surface of a trailer of a tractor-trailer combinationvehicle.

In accordance with any of the embodiments disclosed herein, the surfaceof the trailer is a lateral-facing surface, and wherein the dragreducing assembly is coupled to the lateral-facing surface such thatairflow in a direction of vehicle travel passes from the leading edge ofthe airfoil to the trailing edge of the airfoil.

In accordance with any of the embodiments disclosed herein, the dragreducing assembly may further include a directional biasing memberconfigured to return the airfoil to a neutral rotational position in theabsence of airflow over the upper and lower surfaces.

In accordance with any of the embodiments disclosed herein, the air vanemay be aligned at angle from a direction along the length of the bluffbody.

In accordance with any of the embodiments disclosed herein, the anglemay position the leading portion downward between about 1° and 20°.

In accordance with any of the embodiments disclosed herein, the dragreducing system may further include a biasing member couplable betweenthe air vane and the surface, wherein the biasing member may beconfigured to stop the rotation of the air vane at the second position,and wherein the biasing member may be configured to bias the air vanetoward the first position.

In accordance with any of the embodiments disclosed herein, the biasingmember may stop the rotation of the air vane at an angle between about60° and 90° from the surface of the bluff body.

In accordance with any of the embodiments disclosed herein, the air vanemay further include a gurney strip at a trailing edge of the air vane.

In accordance with any of the embodiments disclosed herein, the flare ofthe leading portion may be positioned at an angle between about 3° and10° from the body portion.

In accordance with any of the embodiments disclosed herein, the flare ofthe lateral portion may be positioned at an angle between about 5° and20° from the body portion.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thepresent disclosure will become more readily appreciated as the samebecome better understood by reference to the following detaileddescription, when taken in conjunction with the accompanying drawings,wherein:

FIG. 1 is side view of a conventional cargo-type trailer;

FIG. 2 is a front perspective view of one representative embodiment of adrag reducing system formed in accordance with aspects of the presentdisclosure;

FIG. 3 is a front perspective view of a drag reducing assembly of FIG.2;

FIG. 4 is a top view of the drag reducing assembly of FIG. 3;

FIG. 5 is a right side view of the drag reducing assembly of FIG. 3;

FIG. 6A is a front perspective view of another representative embodimentof a diffuser plate assembly formed in accordance with aspects of thepresent disclosure;

FIG. 6B is a cross-sectional view of the diffuser plate assembly of FIG.6A taken along section 6B-6B;

FIG. 6C is a cross-sectional view of the diffuser plate assembly of FIG.6A taken along section 6C-6C;

FIG. 7 is a front perspective view of the diffuser plate assembly ofFIG. 6A, showing the diffuser plate assembly mounted to a side panel ofa trailer;

FIG. 8A is a top view of an aerodynamic system showing a plurality ofthe diffuser plate assemblies of FIG. 6A;

FIG. 8B is a right side view of the aerodynamic system of FIG. 8A;

FIG. 9A is a top view of another representative embodiment of anaerodynamic system formed in accordance with aspects of the presentdisclosure, showing a plurality of aerodynamic components;

FIG. 9B is a right side view of the aerodynamic system of FIG. 9A;

FIG. 10A is a top view of another representative embodiment of anaerodynamic system formed in accordance with aspects of the presentdisclosure, showing a plurality of aerodynamic components; and

FIG. 10B is a right side view of the aerodynamic system of FIG. 10A.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings, where like numerals reference like elements, are intended as adescription of various embodiments of the present disclosure and are notintended to represent the only embodiments. Each embodiment described inthis disclosure is provided merely as an example or illustration andshould not be construed as precluding other embodiments. Theillustrative examples provided herein are not intended to be exhaustiveor to limit the disclosure to the precise forms disclosed.

In the following description, specific details are set forth to providea thorough understanding of exemplary embodiments of the presentdisclosure. It will be apparent to one skilled in the art, however, thatthe embodiments disclosed herein may be practiced without embodying allof the specific details. In some instances, well-known process stepshave not been described in detail in order not to unnecessarily obscurevarious aspects of the present disclosure. Further, it will beappreciated that embodiments of the present disclosure may employ anycombination of features described herein.

The present application may include references to directions, such as“forward,” “rearward,” “front,” “rear,” “upward,” “downward,” “top,”“bottom,” “right hand,” “left hand,” “lateral,” “medial,” “in,” “out,”“extended,” etc. These references, and other similar references in thepresent application, are only to assist in helping describe and tounderstand the particular embodiment and are not intended to limit thepresent disclosure to these directions or locations.

The present application may also reference quantities and numbers.Unless specifically stated, such quantities and numbers are not to beconsidered restrictive, but exemplary of the possible quantities ornumbers associated with the present application. Also in this regard,the present application may use the term “plurality” to reference aquantity or number. In this regard, the term “plurality” is meant to beany number that is more than one, for example, two, three, four, five,etc. The terms “about,” “approximately,” “near,” etc., mean plus orminus 5% of the stated value. For the purposes of the presentdisclosure, the phrase “at least one of A, B, and C,” for example, means(A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C),including all further possible permutations when greater than threeelements are listed.

The over-the-highway cargo hauling tractor-trailer combination is onevehicle that experiences excessive aerodynamic drag. Generallydescribed, tractor-trailer combinations typically include a tractor 18having a so-called fifth wheel by which a box-like semi-trailer 24 maybe attached to the tractor 18 by an articulated connection fortransportation of the cargo in the trailer 24, as shown in FIG. 1. Theshape of the conventional cargo trailer is essentially a rectangular boxhaving a flat, rectangular roof 38 and matching floor 40, along withflat, rectangular side panels 42. The fore and aft vertical surfaces 44and 46, respectively, of such trailers 24 are also generally flatrectangular surfaces. The aft section of the trailer 24 is supportablymounted on one or more wheel assemblies, illustrated as components 52and 54.

Conventional large long-haul cargo trailers similar to those describedabove exhibit less than optimal aerodynamic performance during highwayoperation. At highway speeds, these conventional trailers develop asubstantial amount of turbulent airflow throughout regions of thetrailer. This turbulence results in significant aerodynamic drag,increasing both fuel consumption and Nitrogen Oxide (NOx) emissions ofthe tractor 18.

The following discussion provides examples of systems and methods forimproving the aerodynamic efficiency (e.g., reduce drag) of vehicles,such as class 8 tractor-trailer combinations. To improve the aerodynamicefficiency of the combination, examples described herein provide one ormore aerodynamic components positioned on the trailer. In some examplesdescribed herein, the one or more aerodynamic components are in the formof air vanes and airfoils, which are positioned on the sides of thetrailer and/or on the top of the trailer. In some embodiments, the airvanes or airfoils are positioned along the side of the trailer atlocations where off-axis (e.g., at an angle to the longitudinal axis)airflow is present during forward motion of the tractor-trailercombinations. In some embodiments, the off-axis airflow has a generallyupward trajectory as the airflow moves rearwardly along the trailer. Inuse, the one or more airfoils provide a positive or forward thrustcomponent with respect to vehicle movement, thereby reducing the totaleffects of drag on the vehicle. In other uses, the one or more air vanesprovide a break in the airflow to prevent the creation of a vortex onthe roof of the trailer, thereby reducing the total effects of drag onthe vehicle.

Although embodiments of the present disclosure will be described withreference to a cargo trailer, one skilled in the relevant art willappreciate that the disclosed embodiments are illustrative in nature,and therefore, should not be construed as limited to applications with acargo trailer. It should therefore be apparent that the methods andsystems of the present disclosure have wide application, and may be usedin any situation where a reduction in the drag forces on a bluff body isdesirable. In some examples, aspects of the present disclosure can beemployed on the tractor of the tractor-trailer combination.

FIG. 2 illustrates a perspective view of one example of an aerodynamic(e.g., drag reducing) system, generally denoted 110, having a pluralityof drag reducing assemblies 120, or components, associated with acargo-type trailer, according to aspects of the present disclosure. Thetrailer includes a body that defines a cargo carrying interior cavity(not shown). In the embodiment shown, the body is generally rectangularin shape, having a generally planar, vertically oriented front panel114, rear end panels (not shown), generally planar, vertically orientedside panels 116, and a generally planar top panel 112.

As best shown in FIG. 2, the system 110 includes a plurality of the dragreducing assembly 120. FIG. 2 shows the right-side, (when viewing fromthe front of the combination rearwardly), components 120 of the system110 mounted on the side panel 116. It should be noted that thestructures and arrangements of the depicted right-side components 120can be a mirror of right-side components. In other embodiments, anynumber of drag reducing assemblies 120 is suitably used with theaerodynamic system 110. It is noted that the drawings and descriptionsof the right-side components 120 are equally applicable to theembodiments at both sides of cargo-type trailer; however, in some cases,portions may have mirrored geometry for right-side use, for instance,such that the lift of the drag reducing assembly 120 is oriented in thedesired direction to provide the aerodynamic benefit. In furtherembodiments, the drag reducing assemblies 120 may be mounted in auniform pattern or placed at random locations along the panels of thetrailer 112, 114, and 116.

Generally described, the one or more drag reducing assemblies 120 aremounted on the side of the trailer in a spaced-apart manner, as bestshown in FIG. 2. In some embodiments, the one or more drag reducingassemblies 120 are strategically placed along the side of the trailer inpositions that experience off-axis airflow during forward motion of thecombination. In this regard, the off-axis airflow occurs when a portionof the airflow along the trailer does not follow the longitudinal axisof the trailer. The one or more drag reducing assemblies 120 may bemounted to a surface of the vehicle or trailer via mounting posts 124,which are oriented perpendicular to the longitudinal axis of thetrailer, as best shown in FIG. 4. In some embodiments, for stability, amounting plate 122 is used. As will be described in more detail below,the drag reducing assemblies 120 may be configured to rotate about themounting post 124 to provide self-alignment functionality to the dragreducing assemblies 120. In these embodiments, the mounting post 124 mayinclude a bearing to facilitate rotation of the drag reducing assembly120 about the mounting post 124.

Referring to FIG. 3, the one or more of the drag reducing assemblies120, in some embodiments, include a forward thrust generator in the formof an asymmetrical airfoil 130. The airfoil 130 may have a variety ofgeometries, forming many different camber lines according to embodimentsof the present disclosure. In the embodiment shown in FIGS. 3-5, eachairfoil 130 includes an upper surface 162 and a lower surface 164 thatconverge fore and aft at leading and trailing edges 132 and 134,respectively. In the embodiment shown, the upper surface 162 isgenerally convex, while the lower surface 164 is generally concave, withthe airfoil 130 having a chord line below the lower surface 164 thereof.When the airfoil 130 is positioned with respect to the trailer, theupper surface 162 faces generally upwardly of the trailer and the lowersurface 164 faces generally downwardly. As such, during movement of thetrailer, airflow (e.g., wind W) rearwardly from the leading edge 132 tothe trailing edge 134 would progress at a higher velocity along theupper surface 162 as compared to the airflow along the lower surface164, which in turn, generates a lift force F perpendicular to therelative wind W, as best shown in FIG. 5. The lift force F comprises aforce vector (Fz) and a force vector (−Fx). It will be appreciated thatthe negative value of the Fx vector indicates that the Fx vector is inthe opposite direction of drag, otherwise known as thrust. In conditionswhere the −Fx is greater than the additional drag caused by the presenceof the drag reducing assembly 120, total net drag on the trailer isreduced.

The aforementioned properties of the airfoil 130 are directional, suchthat the rotational position of the airfoil 130 with respect to the windW generates different lift and drag characteristics. In someembodiments, the drag reducing assemblies 120 also include a flowalignment vane 138. The flow alignment vane 138, in conjunction with thepivotal mounting provided by the mounting post 124, allow the airfoil130 to self-align to a preferred angle of attack (AOA) with respect tothe wind W created by the forward motion of the combination. In thisregard, the flow alignment vane 138 is configured to provide arotational force R to the components of the drag reducing assembly 120that rotate about the mounting pin 124. In some embodiments, the dragreducing assembly 120 includes a directional biasing member (not shown),such as a torsional spring, configured to reorient the airfoil 130 to aneutral rotational position in the absence of wind over the upper andlower surfaces

Turning now to FIGS. 6A-6C, in accordance with another aspect of thepresent disclosure, a self-deploying vortex diffuser plate assembly 140for a tractor trailer combination or other vehicle. As shown, the vortexdiffuser plate assembly 140 generally comprises a plurality of airvanes, or diffuser plates 142, rotatably coupled to the side panel 116by hinged edges 150 (see FIG. 7). A representative diffuser plate 142will now be described with the understanding that the described featurescan vary and that such variations should be considered within the scopeof the present disclosure. In this regard, the variations can apply toall of the diffuser plates 142 of a particular diffuser plate assembly140 or to just one or more of the individual diffuser plates of adiffuser plate assembly. That is, the described diffuser plate isexemplary only, and a diffuser plate assembly can comprise a pluralityof identical diffuser plates or a combination of more than one diffuserplate configurations.

The diffuser plate 142 has a substantially quadrilateral profile,however, it will be appreciated that the shape one or more of thediffuser plates may vary from the illustrated embodiment to have anysuitable shape. The diffuser plates 145 are preferably made from alightweight, durable material such as sheet metal, fiberglass, polymers,composites, or any other suitable material or combination of materials.

An upper edge of each diffuser plate 142 is attached to the trailer 110by a hinged edge 150 so that the diffuser plate 142 is rotatable betweena first stowed position (shown in broken line in FIG. 7), in which thediffuser plate 142 extends downward from the hinged edge 150 along theside panel 116 of the trailer, and a second deployed positionillustrated in FIG. 7, in which the diffuser plate 142 extends laterallyfrom the side panel 116 of the trailer. As shown in FIG. 7, the hingededge 150 is positioned such that the hinged edge 150 is angled downwardat an angle θ towards the leading edge of the hinge. In the illustratedembodiment, the hinge line forms an angle of about 10° with a horizontalplane; however, the angle θ can vary for alternate embodiments of thediffuser plate assemblies 140 in general, as well as between individualdiffuser plates 142 for a given assembly. In some embodiments, the angleθ is between about 1° and 20°. In other embodiments, the angle θ is anysuitable angle.

As best shown in FIGS. 6A-6C, the diffuser plate 142 includes a leadingedge 144 having an inward flare (see FIG. 6C). Under normal operatingconditions where the airflow is generally longitudinal along thetrailer, the streamwise (forward to rear) flow of air across the inwardflare at the leading edge 144 will provide a biasing force that helps tomaintain the diffuser plate 142 in the first stowed position. In someembodiments, the inward flare of the leading edge 144 is suitablybetween about 3° and about 10° from the diffuser plate 142. In otherembodiments, the leading edge 144 is between about 20 mm and 50 mm inwidth.

The diffuser plate 142 further includes an outward flare along the outeredge 148 (see FIG. 6B). During a yaw (crosswind) condition, an upwardairflow along the side of the trailer may occur. The upward airflowimpacts the outward flare on the outer edge 148 to provide a force thattends to rotate the diffuser plate 142 upward along the hinged edge 150from the first stowed position to the second deployed position. In someembodiments, the outer edge 148 is configured such that airflow greaterthan a predetermined threshold is required to rotate the diffuser plate142 upward to the second deployed position. In some embodiments, theoutward flare of the outer edge 148 is suitably between about 5° andabout 20° from the diffuser plate 142, and the outer edge 148 is betweenabout 20 mm and 50 mm in width. In some embodiments, the trailing edge146 of the diffuser plate 140 includes a gurney strip (not shown), whichis a small tab typically extending at a right angle to the pressure sidesurface of an airfoil to increase aerodynamic performance.

In other embodiments, the diffuser plate 142 rotates from the firststowed position to the second deployed position by the use of amechanical device. In this regard, the deployment of the diffuser plate142 may suitably be a linkage, hydraulic, pneumatic, or a combinationthereof. In these mechanical deployment embodiments, the flares at theleading edge 144 and the trailing edge 148 may be omitted such that thediffuser plate 142 is flat against the surface in the first stowedposition.

As shown in FIG. 7, a travel limiter 152 extends from the side panel 116to the diffuser plate 142. The travel limiter 152 acts as a rotationalstop to hold the diffuser plate 142 at a predetermined angle A when inthe second deployed position under yaw conditions. In some embodiments,the predetermined angle A is between about 60° and about 90°. In theillustrated embodiment, the travel limiter 152 is formed from an elasticmaterial, such as a rubber or a bungee configuration, such that thetravel limiter 152 also acts as a shock absorber. It will be appreciatedthat any number of suitable travel limiter configurations can beutilized to control the deployed position of the diffuser plate 142,including tension springs, torsion springs, bump stops, hinges withintegral stops, or any suitable design.

During normal operation of the tractor trailer, i.e., no yaw condition,the diffuser plates 142 are in the first stowed position. When sopositioned, the diffuser plates 142 extend downward from theirrespective hinged edges 150 and are positioned flat against the sidepanel 116 of the trailer and incur minimal drag. Gravity, and in someembodiments, biasing members or aerodynamic features, maintain thediffuser plates 142 in the stowed position until a yaw condition greaterthan a particular threshold occurs. When a yaw condition occurs, theupward stream of air contacts the outer edges 148 and lifts the diffuserplates 142 to rotate about the hinged edges 150, until further rotationis stopped by the rotational stops 152. When in this second deployedposition, the diffuser plates 142 act to decrease drag and, therefore,increase aerodynamic efficiency in a number of ways.

Turning now to FIGS. 8A and 8B, an aerodynamic assembly 110 is shown. Inthe illustrated embodiment, when the trailer experiences a yawcondition, air flows in an upward and rearward direction along the sidepanel 116 of the trailer. In a baseline configuration (no diffuserplates), this airflow detaches from the top surface 112 of the trailerand forms a conical vortex. With the diffuser plate assembly 130installed as shown in FIGS. 8A and 8B, the upward airflow created by theyaw condition deploys the diffuser plates 142. When deployed to thesecond position, as shown, the diffuser plates 142 act like sails sothat the force of the airflow impinging the lower surface of thediffuser plates 142 creates a resultant force normal to the hinged edge150 of the diffuser plate 142. Although the aerodynamic assembly 110 isshown in FIG. 8A with the diffuser plate assemblies 140 in the seconddeployed position on both sides of the trailer, it should be appreciatedthat in typical airflow conditions, only a single side may have thediffuser plate assemblies 140 in the second deployed position at a giventime. Because the hinged edge 150 is angled downward toward the leadingedge 144 of the diffuser plate 142, the force normal to the hinged edge150 acts in a forward direction. In this regard, the diffuser plates 142act in a cumulative manner to provide a total thrust force on thetrailer in the forward direction. That is, the diffuser plates 142convert some of the energy of the crosswinds into a useful force thathelps propel the tractor trailer forward.

In another aspect, the diffuser plates 142 are also configured toimprove aerodynamic efficiency by diffusing the conical vortex thatforms along the top of the trailer in the baseline configuration. Theconical vortex consumes vehicle energy and increases drag. When thediffuser plates 142 are in the second deployed position, the upwardairflow along the sides of the trailer us broken into sections, whichinhibits vortex formation and decreases drag. Vortex inhibition alsocontributes to higher trailer aft face pressure, which also serves tolower overall vehicle drag as compared to the baseline configuration.

In the illustrated embodiment of FIGS. 8A and 8B, the aerodynamicassembly 110 comprises a plurality of diffuser plates 142 positioned ina line along the top edge of each side panel 116 of the trailer. It willbe appreciated that the number and position of diffuser plates 142 canvary within the scope of the present disclosure. In one alternateembodiment, not shown in the FIGURES, a second row of diffuser platessuitably extends horizontally along a middle portion of the side panel116 of the trailer. Additional rows of diffuser plates may also bepositioned along the top surface of the trailer. These and otheralternate configurations are contemplated and should be consideredwithin the scope of the present disclosure.

Turning to FIGS. 9A, 9B, 10A, and 10B, in accordance with another aspectof the present disclosure, one or more aerodynamic components 240 and340 can be alternatively or additionally provided on the trailer alongthe upper section of the side panel 116 (FIGS. 9A and 9B), or the topsurface 112 thereof (FIGS. 10A and 10B). The one or more aerodynamiccomponents 240 and 340 are spaced apart as the aerodynamic components240 and 340 extend rearwardly. In the embodiments shown, the componentsare in the form of airfoil panels 240 and 340, each having a lower orpressure surface and an upper or suction surface that converge fore andaft at leading and trailing edges, respectively. In the embodimentsshown, the upper surfaces are generally convex, the lower surfaces aregenerally concave, and the airfoils 240 and 340 have a chord line belowthe lower surface thereof. In some embodiments, the airfoils 240 and 340are oriented in order to have a positive or neutral angle of attack inoff axis airflow. It will be appreciated that with suitable angles ofattack, the airfoils will produce a −Fx drag vector, otherwise known asa forward thrust vector, during forward motion of the tractor-trailercombination.

In some embodiments, the airfoils are permanently deployed and extendupwardly from the roof, as shown in FIGS. 10A and 10B. In otherembodiments, the airfoils may be selectively movable between a stowedposition and a deployed position, such that the airfoils extend upwardlyfrom the top surface 112 of the trailer. The airfoils can be deployedtogether or separately. In some embodiments, the airfoils can bedeployed via a four bar linkage arrangement or linear sliders (notshown).

The principles, representative embodiments, and modes of operation ofthe present disclosure have been described in the foregoing description.However, aspects of the present disclosure, which are intended to beprotected, are not to be construed as limited to the particularembodiments disclosed. Further, the embodiments described herein are tobe regarded as illustrative rather than restrictive. It will beappreciated that variations and changes may be made by others, andequivalents employed, without departing from the spirit of the presentdisclosure. Accordingly, it is expressly intended that all suchvariations, changes, and equivalents fall within the spirit and scope ofthe present disclosure as claimed.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A drag reducingassembly, comprising: an airfoil rotatably couplable to a mountingsurface, the airfoil having a leading edge, a trailing edge, an uppersurface, and a lower surface, the airfoil configured to provide a liftforce to the drag reducing assembly as a result of differential airflowvelocity over the upper surface with respect to the lower surface; aflow alignment vane associated with the airfoil configured to provide arotational alignment force to position the airfoil in a directionassociated with the airflow; and a partition panel positioned betweenthe airfoil and the flow alignment vane configured to separate theairflow over the upper and lower surfaces of the airfoil from theairflow interfacing with surfaces of the flow alignment vane, whereinthe upper surface of the airfoil has a longer distance between theleading edge and the trailing edge than the lower surface of the airfoilto generate the lift force.
 2. The drag reducing assembly of claim 1,further comprising a mounting assembly for rotatably coupling theairfoil to the mounting surface, the mounting assembly having a baseplate couplable to the mounting surface and a pin defining an axis,wherein the airfoil is configured to rotate about the axis in reactionto the rotational alignment force.
 3. The drag reducing assembly ofclaim 2, wherein the pin comprises a friction reducing bearing tofacilitate rotation of the airfoil in reaction to the rotationalalignment force.
 4. The drag reducing assembly of claim 1, wherein themounting surface is a surface of a trailer of a tractor-trailercombination vehicle.
 5. The drag reducing assembly of claim 4, whereinthe surface of the trailer is a lateral-facing surface, and wherein thedrag reducing assembly is coupled to the lateral-facing surface suchthat airflow in a direction of vehicle travel passes from the leadingedge of the airfoil to the trailing edge of the airfoil.
 6. The dragreducing assembly of claim 1, further comprising a directional biasingmember configured to return the airfoil to a neutral rotational positionin the absence of airflow over the upper and lower surfaces.
 7. A dragreducing system for a vehicle, comprising: a surface of the vehicle; amounting pin couplable to the surface, the mounting pin defining anaxis; an airfoil rotatably couplable to the mounting pin, the airfoilhaving a leading edge, a trailing edge, an upper surface, and a lowersurface, the airfoil configured to provide a lift force to theaerodynamic assembly as a result of differential airflow velocity overthe upper surface with respect to the lower surface; a flow alignmentvane associated with the airfoil configured to provide a rotationalalignment force to rotate the airfoil about the axis to a positiondirectionally associated with the airflow; and a partition panelpositioned between the airfoil and the flow alignment vane configured toseparate the airflow over the upper and lower surfaces of the airfoilfrom the airflow interfacing with surfaces of the flow alignment vane.8. The drag reducing system of claim 7, further comprising a base plateto stabilize the mounting pin coupling to the surface of the vehicle. 9.The drag reducing system of claim 7, wherein the upper surface of theairfoil has a longer distance between the leading edge and the trailingedge than the lower surface of the airfoil to generate the lift force.10. The drag reducing system of claim 7, wherein the mounting pincomprises a friction reducing bearing to facilitate rotation of theairfoil in reaction to the rotational alignment force.
 11. The dragreducing system of claim 7, wherein the surface of the vehicle is alateral-facing surface, and wherein the drag reducing system is coupledto the lateral-facing surface such that airflow in a direction ofvehicle travel passes from the leading edge of the airfoil to thetrailing edge of the airfoil.
 12. The drag reducing system of claim 7,further comprising a directional biasing member configured to return theairfoil to a neutral rotational position in the absence of airflow overthe upper and lower surfaces.
 13. A drag reducing system for a bluffbody having a length and a height, the system comprising: an air vanehingedly couplable to a surface of the bluff body, the air vane having abody portion, a leading portion, a lateral portion, an upper surface,and a lower surface, the air vane configured to rotate from a firstposition, wherein the air vane is positioned adjacent to the surface, toa second position, wherein the air vane is positioned projecting at anangle away from the surface, wherein the leading portion is flaredinward toward the surface in the first position to provide a force tobias the air vane toward the first position when the airflow along thesurface is aligned with the length of the bluff body, wherein thelateral portion is flared away from the surface in the first position toprovide a force to rotate the air vane from the first position towardthe second position when the airflow along the surface has a directionalcomponent upward along the height of the bluff body.
 14. The dragreducing system of claim 13, wherein the air vane is aligned at anglefrom a direction along the length of the bluff body.
 15. The dragreducing system of claim 14, wherein the angle positions the leadingportion downward between about 1° and 20°.
 16. The drag reducing systemof claim 13, further comprising a biasing member couplable between theair vane and the surface, wherein the biasing member is configured tostop the rotation of the air vane at the second position, and whereinthe biasing member is configured to bias the air vane toward the firstposition.
 17. The drag reducing system of claim 16, wherein the biasingmember stops the rotation of the air vane at an angle between about 60°and 90° from the surface of the bluff body.
 18. The drag reducing systemof claim 13, wherein the air vane further includes a gurney strip at atrailing edge of the air vane.
 19. The drag reducing system of claim 13,wherein the flare of the leading portion is positioned at an anglebetween about 3° and 10° from the body portion.
 20. The drag reducingsystem of claim 13, wherein the flare of the lateral portion ispositioned at an angle between about 5° and 20° from the body portion.